INDEPENDENT CONTROL OF VISUAL AND ELECTROSENSORY FEEDBACK DURING CLOSED-LOOP MULTISENSORY BEHAVIOR IN WEAKLY ELECTRIC FISH

Weakly electric fish (Eigenmannia virescens) are among the foremost candidate animals for studying multisensory integration in closed-loop behavior. During refuge-tracking tasks, these fish utilize both visual and electrosensory information to remain inside a moving refuge. Behavioral measurements show that fish can sustain accurate refuge tracking even when visual or electrosensory input is degraded; however, the mechanisms underlying this robustness remain unclear. To quantitatively investigate multisensory integration and sensory reweighting, we developed a concentric dual-refuge system that enables fully independent stimulation of visual and electrosensory cues. The inner refuge, constructed from agarose, is visually salient but electrically neutral, whereas the outer refuge, made of aluminum, is electrically salient but visually hidden. Each refuge is actuated independently under closed-loop control, allowing precise and selective manipulation of sensory feedback. Sensory reliability was systematically varied by adjusting illumination to degrade visual input and by applying band-limited electrosensory noise (jamming) to degrade electrosensory input. We first validated independent sensory stimulation experimentally in N = 3 fish, demonstrating that fish selectively tracked the motion of each refuge only when the corresponding sensory modality was available. Systematic manipulation of sensory reliability then revealed flexible sensory reweighting: reducing illumination decreased visual contributions while increasing reliance on electrosensory cues, whereas increasing electrosensory jamming produced the opposite effect. Together, these results show that Eigenmannia virescens dynamically adjusts the relative weighting of visual and electrosensory feedback according to cue reliability. The dual-refuge system provides a controlled and versatile framework for probing multisensory integration and sensorimotor adaptation in closed-loop behavior.